Security deposit interest calculator
Estimate the simple interest on a tenant's security deposit between two dates, at an annual rate you enter. The calculator counts the actual days the deposit was held.
Your results
EstimateEstimated interest: $30.00
- Deposit plus interest
- $2,030.00
- Days held
- 365 days
Results are estimates for planning only. They are not legal, tax or investment advice, and they apply no state or local rules. Check your lease, your local laws and a qualified professional before you rely on a number.
How deposit interest is calculated
Interest = deposit x annual rate x days held / 365
This is simple interest: the rate applies to the original deposit only, with no compounding. Days held are the actual calendar days from the date you received the deposit to the date you return it, so a span that includes February 29 counts one more day.
Some states and cities require rental property owners to pay interest on deposits, and they set the rate, how often it is paid and how it is calculated. The calculator uses only the rate you enter. Check the rules where the property is for the rate and method that apply.
Worked example
A rental property owner holds a $2,000 deposit from July 1, 2025 to July 1, 2026 at 1.5% a year.
- Days held: July 1, 2025 to July 1, 2026 is 365 days.
- Interest: $2,000 x 1.5% x 365 / 365 = $30.00.
- Deposit plus interest: $2,030.00.
The estimated interest is $30.00.
Frequently asked questions
Do landlords have to pay interest on security deposits?
It depends on where the property is. Some states and cities require interest, some only for certain buildings or after a minimum holding period, and many have no requirement. Check the rules that apply to your property.
What interest rate should I enter?
Enter the rate that applies to you: one set by a local rule, the rate your bank account pays, or the rate in your lease. The calculator does not look up rates.
Does this calculator compound interest?
No. It calculates simple interest on the original deposit. If your rule or account compounds interest, the amount owed will be a little higher.
How does a leap year affect the interest?
A span that includes February 29 has one extra day. For example, July 1, 2027 to July 1, 2028 is 366 days, so $2,000 at 1.5% earns about $30.08.
Track every security deposit to the dollar
Each lease in KeyRing keeps a deposit ledger: what was received, deductions, refunds, the balance held and the date it is due back. Your first subscription starts with a 14-day free trial.